Melt and then brush on candle wax. I went to a film costuming exhibit once and they had a video playing next to the display for a movie that was supposed to be set in Alaska, showing the costume designers using different consistencies of melted wax, brushed and dripped onto the actor's parka. They used varied coarseness and widths of brush bristles to get a realistic look. A few strategically placed drips looked like the jacket had been wet and then it was so cold that it instantly froze.
Costume Con - Kili in a dress
Atomic Lollipop - Come visit me at the Make-Your-Own-Button free craft booth!
Polar Chill - check out my costume DIY panel and workshop
FanExpo - Iron Man Mark VII version 2, Pacific Rim Jaeger pilot?
FanExpo - fem!Iron Man Mark VII - The Iron Man Armor Project
Atomic Lollipop - Vanellope von Schweetz; raver!Sailor Mars